• Journal of Conservation Science
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• v.22
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• pp.121-134
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• 2008

The mechanism of stone exfoliation and its cause in relation to chemical weathering by soluble salt were studied. Chemical, mineralogical and physical analysis was performed in exfoliation samples from stone monuments. The representative salt is gypsum in the exfoliation samples. In order to understand the salt reaction, stone samples(tuff and granite) were treated with two type of the salt, gypsum and sodium sulfate, which have different solubility. The capillary water uptakes are slight increased in impregnated with Na2SO4 and weathering simulation of two rock types. It means that the rock is deteriorated in the near of the surface by $Na_2SO_4$. $CaSO_4{\cdot}2H_2O$ bring out the thicker exfoliation than $Na_2SO_4$ because it is penetrated into the deeper zone and amount of accumulated salt is more abundant in the inner part than in the near of the surface. The exfoliation was formed in the tuff by salt treatment and 30cycle of weathering simulation, but there are not significant symptoms of exfoliation in the granite by same condition. This result was caused by the different capillary water uptakes and porosity of the rocks. In the tuff, salt solutions are penetrated into the inner part due to its high capillary water uptakes and porosity but the granite, which has low value relatively, can be formed thinner exfoliation.

• Journal of the Korean Electrochemical Society
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• v.2 no.4
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• pp.195-201
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• 1999

The repassivation characteristics of Fe-Cr steels in deaerated 0.1 M $Na_2SO_4$ solution have been investigated with the variation of Cr content, applied potential and Cl- concentration. In the absence of chloride ion, abrading electrode test showed that, slope -n, of log i=k -n log t, a parameter of repassivation rate, approached to -1, regardless of Cr content but as Cr content increased, repassivation current density decreases with increasing Cr content. A.C. Impedance spectroscopy showed that the charge transfer resistance of passive film became higher as Cr content and applied potential increased. However, in the presence of chloride ion, it was observed that chloride ion suppressed the passive film formation, whose effect became greater with increasing applied potential.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.34-35
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• 1999

• 한국전기화학회:학술대회논문집
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• 1999.04a
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• pp.39-39
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• 1999

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.407-413
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• 1998

The influence of the anion composition of simulated acid rain on cation leaching of two soils with different surface charge properties was examined. Four mixtures of mole ratio of $SO_4:NO_3$(1:0, 2:1, 1:1, 0:1) with pH 2.0 simulated acid rain were applied to an Inceptisols(Gyuam series) and Andisols(Pyeongdae series). The Andisols had higher $SO_4{^{2-}}$ adsorption capacity than the Inceptisols because of its higher point of zero charge(PZC, pH 6.5) than Inceptisols(PZC pH 3.1). Cation leaching in Andisols varied directly with the $NO_3$ content of the leaching input due to higher mobility of $NO_3$ compared with $SO_4$ that was absorbed. The pH of the Andisols was higher with the addition of $Na_2SO_4$ than the addition of $NaNO_3$ indicating that this soil behaves as a base and has a high $SO_4$ adsorption capacity. The relative $NO_3{^-}/SO_4{^{2-}}$ content input had no effect on cation leaching of the Inceptisols. Amounts of leaching on the Andisols by simulated acid rain were higher than Inceptisols. This experiment explained that anion composition of acid rain plays a significant role in the cation leaching of soils which are able to adsorb $SO_4$.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.33-39
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• 2000

Gordona sp. MS6, desulfurizing petroleum, can convert dibenzothiophene (DBT) to 2-hydroxybiphenyl (2-HBP) and sulfate. In this study, the effect of DBT degradation product on DBT desulfurization activity was investigated. When $Na_2$SO$_4$ and DBT were simultaneously added in the medium sulfur sources, specific growth rate of strain MS6 was doubled compared to not adding $Na_2$SO$_4$. But, sulfate inhibited DBT desulfurization rate, furthermore, when 0.05 g/L $Na_2$SO$_4$ was supplied DBT desulfurization rate decreased down to 40%. When 2-HBP and its derivative, 2, 2'-dihydroxybiphenyl (DHBP) were not added, DBT desulfurization rate was 5.0 $\mu$mol L$^{-1}$ㆍh$^{-1}$. With the increase of 2-HBP and DHBP concentration, DBT desulfurization rate was decreased. No DBT desulfurization activity of Gordona sp. MS6 was observed when initial concentration was over 0.15 mM 2-HBP and 0.8 mM DHBP [Gordona sp., Desulfurization, Dibenzothiophene, 2-Hydroxybiphenyl, Sulfate].

• Journal of Environmental Science International
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• v.26 no.5
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• pp.563-572
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• 2017

The Electrocoagulation-Flotation (ECF) process has great potential in wastewater treatment. ECF technology is effective in the removal of colloidal particles, oil-water emulsion, organic pollutants such as microalgae, and heavy metals. Numerous studies have been conducted on ECF; however, many of them used a conventional plate-type aluminum anode. In this study, we determined the effect of changing operational parameters such as power supply time, applied current, NaCl concentration, and pH on the turbidity removal efficiency of kaoline. We also determined the effects of different electrolyte types (NaCl, $MgSO_4$, $CaCl_2$, $Na_2SO_4$, and tap water), as well as the differences caused by using a plate-type and mesh-type aluminum anode, on the turbidity removal efficiency. The results showed that the optimal values of ECF time, applied current, NaCl concentration, and pH were 5 min, 0.35 A, 0.4 g/L NaCl in distilled water, and pH 7, respectively. The results also revealed that the turbidity removal efficiency of kaoline in different electrolytes decreased in the following sequence, given the same conductivity: tap water > $CaCl_2$ > $MgSO_4$ > NaCl > $Na_2SO_4$. The turbidity removal efficiency of the mesh-type aluminum anode was significantly greater than the plate-type aluminum anode.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.3
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• pp.140-151
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• 1999

Groundwater samples from the southern area composed of andesitic rocks and the northwestern area composed of granite in Pusan city, have been collected and analyzed. According to the Piper diagram. groundwater in the southern area belongs to Ca$\^$2＋/－HCO$_3$$\^$－/ and Ca$\^$2＋/－(Cl$\^$－/＋SO$_4$$\^$2－/) types, and that in the northwestern area mostly belongs to Ca$\^$2＋/－HCO$_3$$\^$－/ type and partly Na$\^$＋/－HCO$_3$$\^$－/ type. Two factors (factor 1 and factor 2) were obtained from the result of the factor analysis in the southern area. Factor 1, consisting of Mg$\^$2＋/, Ca$\^$2＋/, Cl$\^$－/, SO$_4$$\^$2－/, NH$_4$$\^$＋/, EC and NO$_3$$\^$－/ is represented by the dissolution of Ca-plagioclase and calcite, and the influence of anthropogenic sources. Factor 2, consisting of K$\^$＋/, Na$\^$＋/. SiO$_2$, SO$_4$$\^$2－/, and HCO$_3$$\^$－/ is mainly represented by the dissolution of feldspar. Three factors were obtained from the result of the factor analysis in the northwestern area Factor 1, consisting of Na$\^$＋/, K$\^$＋/, NH$_4$$\^$＋/, Cl$\^$－/, SO$_4$$\^$2－/ and NO$_3$$\^$－/ explains dissolution of plagioclase and mica, the influence of anthropogenic sources and salt water. Factor 2, consisting of Ca$\^$2＋/ and HCO$_3$$\^$－/ explains the dissolution of Ca-plagioclase. Factor 3, consisting of Mg$\^$2＋/ and SiO$_2$, explains the dissolution of silicate minces. and contaminants. Based on the phase stability diagrams, groundwater both in the southern and in the northwestern area is mostly in equilibrium with kaolinite. Cl$\^$－/ with respect to Na$\^$＋/, Ca$\^$2＋/, Mg$\^$2＋/, K$\^$＋/, SO$_4$$\^$2－/ and HCO$_3$$\^$－/ indicates that both the northwestern area and the southern area are influenced by the salt water.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.155-160
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• 2004

Permeation experiments of a commercial nanofiltration membrane (nominated as ESNA 1) were carried out with aqueous solutions of various single salts, that is, five chlorides (NH$_4$Cl, NaCl, KCl, MgCl$_2$ and $CaCl_2$), three nitrates $(NaNo_3,\;Mg(No_3)_2\;and\;Ca(NO_3)_2)\;and\;three\;sulfates\;((NH_4)_2SO_4,\;Na_2SO_4\;and\;MgSO_4)$. The experimental results showed that (1) the permeate volume flux of the ESNA 1 membrane increased and decreased with the growth of the applied pressure and the feed concentration of salts, respectively. The real rejection of ESNA 1 membrane to most single salts increased with the growth of the permeate volume flux. (2) The reflection coefficients of ESNA 1 membrane to chlorides, nitrates and sulfates are 0.97, 0.96 and 0.99, respectively. The solute permeability of most salts except for magnesium and calcium salts increased with the growth of feed concentration. (3) The sequence of the rejections of ESNA 1 membrane to anions is $R({SO_4}^{2-})>R(CI)>R(NO_3)$ at the same feed concentration. While the sequence of the rejections to cations is cataloged into two cases: $R(Na^+)>R(K^+)>R(Mg^{2+})>R(Ca^{2+})$ at the concentration of 10 mol/$m^3$ and $R(Mg^{2+})>R(Ca^{2+})>R(Na^+)>R(K^+)$ at the concentration of 100 mol/$m^3$. The separation capability of a NF membrane is usually affected by the electrostatic effect and the steric-hindrance effect. In this case, the electrostatic effect is the major factor at low concentration and the steric-hindrance effect is the major factor at high concentration. Both the specific sorption and the hydration also reasonably influenced the separation performance of NF membrane to salts.

• Microbiology and Biotechnology Letters
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• v.4 no.3
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• pp.99-104
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• 1976

Experiments were carried out to establish the effects of acids in neutralization after alkaline treatment of rice straw, with which cellulosic single cell protein can be produced by cellulose utilizing bacteria, Cellulomonas flavigena KIST 321, previously isolated by authors. Following results were obtained. 1. Rice straw as carbon source was pretreated with 10 volumes of 1 normality of NH$_4$OH or NaOH(NaOH/substrate：40％, and then washed with water or neutralized with H$_3$PO$_4$, H$_2$SO$_4$, HCl and CH$_3$COOH. Among the above mentioned methods, neutralization with H$_3$PO$_4$after alkaline treatment was proved to be the most effective on its digestibility and SCP production. Dry cell 12.28g/$\ell$ and 78％ digestibility were obtained. 2. When rice straw was treated with NaOH solution, the result suggested that the productibity of cell-mass was attained on treatment of rice straw with 6％ of NaOH (NaOH/substrate ratio) for 15～24hrs at room temperature. 3. When rice straw was treated with NaOH, a volume of water to substrate is adequate by two or three fold and the amount of NaOH can be economized up to 5％ for the weight of rice straw. 4. The steaming of rice straw at 121$^{\circ}C$ for 30min. in alkaline treatment of rice straw gave the similiar effectiveness to that at room temperature for 15～24hrs. and accelerated the sterilization of the substrate. 5. Finally, the level of inorganic phosphate in a medium was investigated. 11.2g of dry cell was produced at the concentration of 0.2％, phosphate (phosphorous level 0.04％) in medium even though treated rice straw was neutralized with HCI instead of H$_3$PO$_4$, and 12.2g/$\ell$ at the concentration of 0.3％ phosphate (phosphorous 0.04％) on neutralization with H$_2$SO$_4$.